676 
There is a ftriking contraft between the 
22d of June and the 24th of December; 
fhe latter being 53°, and the former only 
net 
The lowett point of the barometer was 
on the roth and ssth of November. at 
23°36 inches. 
If ina courfe of time it fhould be ob- 
ferved that the wind at any place fhould 
blow as many days north as fouth, and 
the fame number eaft and welt, it could 
not be faid there were any prewailing 
ewinds. at that place, regard being had to 
the duration of the wind only ; but fhould 
we find the wind to blow three days from 
the weft, to one in each of the other 
points, we fhould juftly fay that the pre- 
vailing wind was weit, But fuppofe, as 
it will generally happen, that the num- 
bers exprefling the days of wind blowing 
from the different points fhould not ex- 
actly meafure each other ; thus, fuppofe 
there thould be feventeen: days weft wind 
and feven days fouth, pow the prevailing 
wird would be fomewhere between thefe 
two points; the diftance of which from 
each would be inverfely proportional to 
the number of days blown from each, 
(regard being had to time only) or S. W. 
by W.3 W.3 but it will not happen 
neither for a long time that the whole of 
the wind fhould be fhared between two 
contiguous cardinal points: thus, fuppofe 
the wind fhould. be fix days north and 
fix days fouth, and three days weft ; now 
I fay, that in refpect of thefe fifteen days, 
the prevailing wind is weft, becaufe the 
fix north and fix fouth deftroy each other, 
like the oppofite figns in algebra. Or, we 
may compare it to a veffel ar fea, blown 
by a north wind fix days, and fix by a 
fouth wind, and weft wind three days ; 
now, all ether things being equal, the 
weft will prevail, and the veffel will be 
exa@tly in the fame latitude, and have 
made three days tothe eaft. Juf in this 
way may we make ule of my tables of 
approximation of the wind to the cardinal 
points explained in Monthly Magazine, 
Vol. X. page 1083 and confider’ them 
like the eaftings and weltings, &c. in 
working a traverfe, by taking the fmalle& 
from the largeft of the oppofites, and 
finding the ratio of the remaining dif- 
ferences; like Morveau, by his quiefcents 
and divellants in his diagram of com- 
Mr. Bevan's Meteorological Regifter. 
pound affinities, working only by the furs 
pluffes. . 
An example or two perhaps may make 
it plain to thofe who are proof againft a 
mere precept: let us, for inflance, take 
the firft ten days of July in the table 
above: i 
N. 3—E. 1 
S. 15 — W. 21 
Surplus S. 12 — W. 20 
So that the prevailing wind will be! fome 
where between fouth and weft, and fo 
much nearer welt than fouth, as 296 
exceeds 12; or, to find the very point, 
12+20:8 :::12:3::20: 5, or that ont 
of the eight points between fouth and weit 
it is three towards the fouth and five fo- 
wards the welt, or S.W. by W. - 
Again, fuppofe we take the whole year. 
1803— 
N. 338 — E. 108 
S. 482 — W.451 
S.144 — W.253 
Now 144 
253 
397: 83: 1443 2°9 3:253: 53 ze 
S. W. by W. js W. ’ 
One more will fufice.—The -firt ten 
days in O&tober 
Nite 2B.) 2 
S. 6 :° W.20 
N. 62) We 
Here 6 +18 : 8::6:2 :: 18:6, 
W.N.W. 
Thus we fhall be able to fum up the 
whole average wind for a year, with the 
fame eafe, and in the fame line, with the. 
barometer and thermometer, &c. &c. and 
can compare one year with another, and - 
one place with another, by a fingle line, 
and trace the motion of this average point 
perhaps till we find its laws and pericd, 
or 
a 
It will be feen, by infpeéting the above. 
table, that the average wind for this 
place for four years is very nearly S. W. 
by W. For1800=8.W. For 1801 | 
=S.W.byS3W. For 1802, fame as 
1808. 
Sir, your's, cc. 
Leighton, os 
: B. Bevan. 
Fan. D> 1304. 
Ta 
